This invention relates to mechanical vibrators and is directed more specifically to improvements in a vibrator of the type wherein the forces exciting the vibrations are generated by rotating unbalanced masses. The vibrator according to the invention is suitable for use, for example, in a vibratory compactor of the roll type which combines static weight with the dynamic force generated by the vibrator for compaction or densification of soils.
In a well known type of vibrator employed for vibratory roller compactors, vibrations are produced by rotation of eccentric mass about a fixed axis. The vibratory force developed by this type of vibrator can be defined as EQU F = mr.omega..sup.2
where F is the vibratory force, m is the mass, r is the eccentricity of the mass from the axis of rotation, and .omega. is the angular velocity.
For controlling the vibratory force and the frequency of vibrations independently of each other in this type of vibrator, the mass moment mr and the angular velocity .omega. must be controlled separately. If the mass moment mr is a constant, the vibratory force F will vary in proportion to .omega..sup.2. In other words, the vibratory force will be determined in accordance with the frequency.